The correct answer is that SR-MPLS uses a segment list to encode the path in the packet header and does not require LDP for label distribution. Unlike traditional LDP-based MPLS, which relies on a separate label distribution protocol to advertise bindings hop-by-hop, SR-MPLS encodes the entire forwarding path as an ordered list of segments—essentially a stack of labels—directly in the packet header. This eliminates the need for LDP or RSVP-TE because the IGP (OSPF or IS-IS) automatically assigns and distributes the labels using extensions like the Segment Routing Global Block. On the Cisco SPCOR 350-501 exam, this concept tests your understanding of how SR simplifies the control plane while enabling source-routed traffic engineering. A common trap is assuming SR still needs LDP for label exchange or that it cannot support TE or fast reroute—both of which it can, via SR-TE policies and TI-LFA. Memory tip: think “No LDP, just a stack—SR puts the path in the packet’s back.”
350-501 Services Practice Question
This 350-501 practice question tests your understanding of services. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO of the following are characteristics of Segment Routing (SR-MPLS) compared to traditional LDP-based MPLS? (Select two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
SR-MPLS does not require LDP or RSVP-TE for label distribution.
Options A and E are correct. SR-MPLS uses a segment list (stack of labels) encoded in the packet header, and it does not require LDP or RSVP-TE for label distribution; labels are assigned by the IGP (OSPF or IS-IS). Option B is wrong: SR-MPLS can do traffic engineering via SR-TE policies. Option C is wrong: SR-MPLS supports fast reroute (TI-LFA). Option D is wrong: SR-MPLS can support any label range (16-1,048,575).
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
SR-MPLS requires a dedicated label range from 16 to 99.
Why it's wrong here
No such restriction.
✗
SR-MPLS does not support traffic engineering.
Why it's wrong here
SR-MPLS supports traffic engineering via SR-TE policies.
✓
SR-MPLS does not require LDP or RSVP-TE for label distribution.
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Got this wrong? Here's your next step.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-501 OSPF questions on adjacency and route selection.
Services — This question tests Services — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: SR-MPLS does not require LDP or RSVP-TE for label distribution. — Options A and E are correct. SR-MPLS uses a segment list (stack of labels) encoded in the packet header, and it does not require LDP or RSVP-TE for label distribution; labels are assigned by the IGP (OSPF or IS-IS). Option B is wrong: SR-MPLS can do traffic engineering via SR-TE policies. Option C is wrong: SR-MPLS supports fast reroute (TI-LFA). Option D is wrong: SR-MPLS can support any label range (16-1,048,575).
What should I do if I get this 350-501 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-501 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Match each Segment Routing component to its function.
medium
Why : These are key elements of Segment Routing in service provider networks.
Last reviewed: Jun 24, 2026
Question Discussion
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This 350-501 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-501 exam.
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